Shutters of this type are already known, which are also referred to as "drum shutters", in which the obturation wall of the shutter is normally a length of a cylindrical wall which pivots inside a length of a cylindrical wall forming part of a distribution casing, the two cylindrical walls being coaxial.
Generally the cylindrical wall of the casing has several passage openings which are spaced apart angularly and which can be closed off or opened selectively by the obturation wall of the shutter according to the angular position taken by the latter. These devices have the advantage of enabling all the air distribution to be controlled with a single shutter placed in a single casing, which simplifies the design and also affords greater compactness.
One of the problems posed by this type of shutter is that of airtightness. It is in fact necessary for the shutter to guarantee perfect airtightness of the different air passage openings, also referred to as "vents", when the shutter is in a closure position.
In the past, this airtightness is provided by a joint, for example by a foam joint covered with a polyamide cloth, bonded externally to the periphery of the obturation wall of the shutter.
Such a joint theoretically guarantees good airtightness, but at the cost of a high maneuvering force, because of the friction generated by the joint.
In addition, this joint has a tendency to lose its sealing capability because of wear, and is sensitive to ambient humidity.
It must also be stated that producing such a joint is tricky and that the resulting cost is relatively high.